Audio playing through monitor not headphones

[BenTheFourFingered]

I bought a custom PC a few weeks ago and using a TV as a monitor, the TV has been playing up a bit and sometimes the picture will cut out. But when I plug my headphones into the tower and listen to music or play games, after about 20 minutes it will start to play through the monitor and it can't detect my headphones. If I plug the headphones back in, I get a message saying that it has been plugged in but shortly after I get another saying that it has been unplugged. Is this the PC or TV acting up? Thanks.

 

[popatim]

Its your pc's jack or the headphones.